Method for the production of cast iron in cupola furnaces



Patented May 16, 1939 2,158,5lli

FFICE METHOD FOR- THE PRODUCTION OF CAST IRON IN UUPOLA FURNACES Karl Lauer, Gelsenkirchen, Germany, assignor to I Deutsche Eisenwerke vAktiengesellschaft, Mulheiim-on-the-Ruhr, Germany, a body corpora e No Drawing. Application June 17; 1938, Serial No. 214,317. In Germany June 21, 1937 7 Claims. (01. 75 43) It is known, to produce superheated cast iron analysis of the molten iron according to the iron meltings, with low carbon content and consecharge."

quently a high- -grade cast iron in cupola furnaces by adding to the iron charge more or less large castings, in the method according to the invention the quantity of the steel wool or the like to .be added in loose state must be so chosen that its loss only results in an increase of the melting temperature without appreciably infiuencing the When alow carbon content is not desired or desirable, it was hitherto not possible to attain properties of the cast iron being influenced by the steel wool' or similar additiona very hot, thinly liquid yet soft, that is normally high or highly carbonized iron can be produced, which in many cases is of great advantage and par 5 quantities of steel scrap or of other iron poor in such high melting and running temperatures as carbon and in melting these charges only with in the case of charges containing steel, because the quantities of coke usual for the remelting of in these instances essential steel additions to the pig iron or pig iron and broken cast iron and charges had to be avoided. In these cases is with the quantities of air corresponding to this given an exceedingly important application for quantity of coke. The steel scrap or iron poor the invention, in that the inventor has unexpect- 10 in carbon is, in this method, charged with the edly discovered that in the cupola furnace a soft, iron charge as a component of this charge and that is normal or highly carbonized cast iron as far as possible in relatively coarse and large with high temperature can also be melted if steel cross-sectional lumps adapted to the diameter of or other iron, poor in carbon, is added to the the furnace. quantity of coke usual for remelting pig iron or 15 It has also been tried to employ the steel scrap pig iron and broken cast iron, in the form of in the form of steel chips as a component for the wool or in similar large surface and small crosscharge, and proposals of this kind are to be sectional form. This iron poor in carbon added found in literature. For this purpose the steel preferably mixed with the charge coke in the chips are introduced into the melting zone of the loosest possible state quickly attains very high 20 furnace either in compressed state produced by temperatures under the action of the glowing means of an eccentric press-or are charged with coke and burns in the melting zone under the the iron charge into the furnace, pressed as action of the oxygen of the blast thereby developtightly as possible into suitable sheet iron coning high specific heat, with the result that it is 5 tainers or briquetted into a compact shape with utilized in an excellent manner for increasing or without binding agent, an increase of the the temperature or for superheating the actual quantity of charge coke being mostly considered, iron charge, without thereby influencing. in an to be necessary. In all these remelting methods unfavourable manner the softness or the carbon of steel chips, however, a considerable loss of iron content of the product.

cannot be avoided. For attaining a noticeable effect quantities of 3 The inventor has now discovered that, entirely steel wool or the like amounting to 5% of the contrary to all former opinions and general praccharge coke weight are already suflicient; howtice, the heat liberated during the burning of ever, it is also possible to add to the usual quansteel can be utilized in an excellent manner for tity of charge coke steel wool or the like up to the smelting process in the cupola furnace if steel 30% and more of the weight of the charge coke. 35

or other iron poor in carbon is, according to the Wastes of other easily oxidizable metals, such present invention, charged into the furnace as as aluminium or the like, can also be used inadditional heat carrier in the'form of steel wool tead of or together with steel wool or t or in similar large surface, small cross-sectional, large Surface, Small cross-Sectional bulky Iron 0 bulky form and in the loosest possible state, to- Wastes in loose formgether with the charge coke i. e. the quantity of If cupola, furnace lsalready'norma'uy i ated with considerable excess draft, this quantity coke to be used in the furnace for each iron nth rt ed um t r th charge, and mixed therewith. Whereas, in the gig g g gig g g f zg s kgown fi ig gzg jfi i 3321: 3 5 3: crease the quantity or pressure of the air or 45 c 8 s e a n e both so as to have at disposal the oxygen necesone produFe hlgh meltmg and conse' sary for the burning of the steel wool or the like. quenfly hlgh runnmg temperature on the The advantage of the new method in the proother hand, to reduce the carboncontent'and to duction f cast iron from pig iron and broken the produce high grade properties in the cast iron is thatwithout the desired quality and 50 additional heat generating means mixed with that quantity of charge coke, which is normally used for the remelting o! pig iron or pig iron and broken cast iron.

2. A method as specified in claim 1, in which iron poor in carbon is used as easily oxidizable metal.

3. A method as specified in claim 1, inwhich 20 steel wool is used as easily oxidizable metal.

4. A method as specified in claim 1, in which for the production of normal or higher carbonized cast iron the quantities of easily oxidizable metals charged into the furnace mixed with the charge coke are selected so that their burning only increases the melting temperature without essentially influencing the carbon content of the molten iron.

5. A method as specified in claim 1,' in which iron poor in carbon is used as easily oxidizable metal and is mixed with the coke in a quantity of from 5% to 30% of the weight of the charge coke.

6. A method as specified in claim 1, in which a mixture of steel wool and aluminium is used as easily oxidizable metal.

7. A method as specified in claim 1, in which a mixture of iron poor in carbon and aluminium is used as easily oxidizable metal.

KARL LAUER. 

